<div class="grid">
	<div>a</div>
	<div>a</div>
	<div>a</div>
	<div>a</div>
	<div>a</div>
	<div>a</div>
</div>
<style>
.grid{
	display:grid;
	grid-template-columns:1fr 1fr 1fr;
	grid-template-rows:1fr 1fr;
	grid-gap:0.5em;
}
.grid > *{
	background-color:darkgray;
	color:white;
	padding:2em;
	border-radius:0.5em;
}
</style>